textproduct: Rapid City

KEY MESSAGES

- Critical fire weather conditions both Saturday afternoon and evening and Sunday afternoon/evening for portions of northeastern Wyoming and southwestern South Dakota due to gusty winds, low relative humidities, and warm temperatures.

- A few isolated dry-leaning thunderstorms are possible late Saturday afternoon into Saturday evening. If storms occur, lightning and a few wind gusts in excess of 45 MPH will be possible.

- An upper trough will bring slightly better rain chances to the region early next week with semi-unsettled conditions the rest of the week.

UPDATE

Issued at 1131 PM MDT Fri Apr 10 2026

No major changes this evening to the fire weather forecast or expectation for critical fire weather conditions this weekend. Ongoing RED FLAG WARNING for Saturday afternoon and evening continues to look good. Considered slight expansion to the east, but current warning covers the area with highest confidence of overlap of critical RHs/winds best for now. Saturday evening into the first half of Saturday night...all high-res CAMs for multiple runs now are supporting showers and a few isolated thunderstorms across the region generally tracking from southwest to northeast between 4 PM and 1 AM. Overall confidence on occurrence and timing at any given location remains on the low side (overall risk is at about 20%), and it's likely that not everyone will be affected, but given very steep low-level lapse rates, modest inverted-V forecast soundings, and decent DCAPE values, any storms that do manage to develop will pose primary threats of lightning and wind gusts in excess of 45 MPH. This is also heavily hinted at in the HREF wind gust ensemble max, which actually paints a few cores gusting to 60 MPH. We're starting to message this conditional yet potentially impactful potential across our products/forecasts for the public, fire partners, and airports, and will continue closely watch and refine timing as the window of concern approaches. Made some adjustments to PoPs and QPF to capture this scenario Saturday evening, and also massaged temperatures a couple degrees higher than NBM guidance for Sunday, especially considering expectation of plenty of sunshine.

DISCUSSION

(This Afternoon Through Thursday) Issued at 1115 AM MDT Fri Apr 10 2026

Upper trough will dig into the western CONUS, forcing the upper ridge east. This will support warm and mainly dry weather this weekend. Although a few isolated showers will be possible late Sat. Breezy return flow ongoing today as pressure falls ensue. Breeziest winds will be across NW SD into this evening. Breezy winds will continue overnight, esp over scentral SD. This will help keep temps milder as WAA revs up. Much warmer Sat as deep layer mixing times with the the thermal ridge. Highs will reach into the 70s and 80s most places. A weak lead impulse will shift the lee-side trough into the FA later in the afternoon. Enough high level moisture and instability will be in place to force isolated showers and perhaps a few TS, esp over NE WY and far SW SD. Gusty winds would be expected with any convection that does develop given inverted V profiles. Any shower activity will carry northeast through the evening into western SD. Sfc trough will push into the area and stall as the main upper trough pushes east into the Rockies. This will support another mild day across the region Sunday with highs in the 70s, a few low 80s in scentral SD. Cool front starts to progress east into the area Monday with increasing upper level moisture. This could support a few showers by afternoon into the overnight hours, with better chances Tues as the main batch of upper level forcing/lift spreads over the region. Certainly not a wash out, but a few locations could see a few tenths. Cooler for the second half of the week with active westerly flow supporting a series of troughs through the area.

AVIATION

(For the 06Z TAFS Through 06Z Saturday Night) Issued At 1131 PM MDT Fri Apr 10 2026

Breezy conditions will continue tonight, Saturday, and Saturday night across the region, with a switch from SE to SW currently progged for about 14z/8am at KGCC and 18z/noon Saturday at KRAP. After reviewing the 00z HREF suite of CAMs, we have gone ahead and introduced a PROB30 period at both TAF terminals Saturday evening to capture the potential for a few isolated thunderstorms to track northeast across the region. Overall confidence on timing and occurrence still leans low, but IF thunderstorms occur near or over a terminal, model soundings support the potential for wind gusts of at least 40kts given a dry and unstable low-level environment. The timing window will continue to be refined (and shrunk if possible) as trends in the guidance and forecast confidence allow. Despite this conditional potential, confidence in VFR conditions remains high throughout the TAF period and into Sunday.

FIRE WEATHER

Issued At 1115 AM MDT Fri Apr 10 2026

Gusty southwest winds, very dry air, and lack of appreciable green up will support critical fire weather conditions Saturday over portions of northeast WY and western SD. In addition, there is a the potential for late afternoon/early evening isolated dry TS, especially over northeast WY and far SW SD. A red flag warning has been issued for this. Continued dry and breezy conditions are expected Sunday, esp south of I90 where critical fire weather conditions are likely again. A low pressure system will move into the region early next week, potentially bringing some wetting rains to the area. Cooler and unsettled for the rest of the week.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning from noon to 8 PM MDT Saturday for SDZ320>322- 324>326-329-332. WY...Red Flag Warning from noon to 8 PM MDT Saturday for WYZ314>317.